1. Field of the Invention
The present invention relates to a sample probe for extracting a fluid sample from a fluid supply source and, in particular, a back flushable sample probe which can be readily freed of debris by flushing fluid through the probe in a reverse direction.
2. Description of the Related Art
Sampling devices for removing a fluid sample from a source of flowing fluid, e.g., a pipe or conduit, may require filtering or straining of heterogeneous material from the fluid sample to create a homogeneous yet representative sample prior to collection and analysis. Many conventional sampling devices employ a mesh type strainer or similar porous medium to remove debris from fluid to be collected and sampled. In certain fluid processing systems, such as municipal wastewater sewage treatment systems and storm sewer systems, the fluid to be sampled contains debris of significantly varying sizes. In such systems, the filter or strainer can become clogged very quickly, leading to an increase in pressure at the strainer and an inability to obtain a fluid sample passing through the strainer. Strainer devices for such systems may employ a back flushing mechanism to remove material sticking to the strainer. However, even back flushing is ineffective in situations where material becomes severely lodged or jammed within the holes or apertures of the strainer. In those situations, the sample device must be disengaged and brought offline from the fluid supply source so that the strainer may be removed and physically and/or chemically treated to dislodge material plugging the apertures of the strainer.
A sampling device including a strainer is therefore desirable that can effectively remove varying types of debris from a fluid sample and that can readily dislodge material stuck within the apertures of the strainer without the need to disengage the device from a fluid supply source.
Therefore, in light of the above, and for other reasons that become apparent when the invention is fully described, an object of the present invention is to provide a fluid sample probe securable to a fluid supply source that effectively filters or strains a fluid sample from the fluid supply source and delivers the fluid to a fluid collection site.
Another object of the present invention is to provide a back flushing feature within the sample probe that effectively dislodges any material that may become stuck within the strainer of the sample probe.
A further object of the present invention is to effectively dislodge material stuck within the sample probe without requiring disengaging of the sample probe from the fluid supply source.
The aforesaid objects are achieved individually and in combination, and it is not intended that the present invention be construed as requiring two or more of the objects to be combined unless expressly required by the claims attached hereto.
In accordance with the present invention, a back flushable sample probe is provided to filter or strain a fluid sample from a fluid supply source, such as a fluid conduit, for delivery to a fluid sample collector. The sample probe includes a fitting to withdraw the fluid sample from the fluid supply source for delivery to a sample collector and a strainer assembly disposed within the fitting and including a first member and a second member. The first member moves within the fitting to releasably engage with the second member which is secured and immobilized within the fitting. A strainer is formed and becomes operable to effectively remove debris from the fluid sample upon engagement of the first member with the second member. Back flushing is also easily accomplished by reversing the direction of fluid flow within the fitting to force fluid from the fitting back into the fluid supply source. Back flushing of fluid in the sample probe disengages the first member from the second member and releases any debris that may be clogging the strainer formed at the engaging interface between the first and second members. In a preferred embodiment, the first member includes a generally spherical valve member and the second member includes a ring having a plurality of serrations extending from the ring to engage with the first member, such that the engaging interface between the serrations and the spherical valve member forms a series of apertures or strainer perforations that permit sample fluid to pass while preventing debris entrained within the sample fluid and larger than the strainer apertures from passing beyond the second member.
The above and still further objects, features and advantages of the present invention will become apparent upon consideration of the following detailed description of a specific embodiment thereof, particularly when taken in conjunction with the accompanying drawings wherein like reference numerals in the various figures are utilized to designate like components.